Capillary tube assembly for evaporators



April 24, 1962 J. KARMAZIN 3,030,782

CAPILLARY TUBE ASSEMBLY FOR EVAPORATORS Filed March 3l, 1959 2 Sheets-Sheet 1 INVENT'oR.

Apri'l 24, 1962 1. KARMAzlN CAPILLARY TUBE ASSEMBLY FOR EvAPoRAToRs Filed March 31, 1959 2 Sheets-Sheet 2 INVENTOR. J?? /drrv'rdzzw nited States This invention relates to evaporators of the type used in refrigerating apparatus, and more particularly to an evaporator with an improved capillary tube assembly. This application is based on my prior copending application Serial No. 541,583, now U.S. Patent No. 2,896,429, granted July 28, 1959. i

It is an object of this invention to provide an improved evaporator construction of this character which includes capillary tubes which are on the inlet manifold for liquid refrigerant Iat the inlet ends of the refrigerant conduits, these capillaries in one form of the invention being removable for maintenance purposes.

Other objects, features, and advantages of the present invention will become apparent from the subsequent description, taken in conjunction with the accompanying drawings.

In the drawings:

FIGURE 1 is a side elevational view of an evaporator core provided with the capillary tubes of this invention;

FIGURE 2 is a top plan view of the evaporator of FIG- URE l;

FIGURE 3 is an end elevational view in the direction of the arrow 3 of FIGURE 2;

`FIGURE 4 is a detailed cross-sectional view taken along the line 4 4 of FIGURE 3 and showing the construction of an intake manifold as well as the capillary tubes of this invention; and

FIGURE 5 is a detailed cross-sectional view similar to FIGURE 4 but showing a modified form in which the capillaries are constructed in a removable manner.

rIhis invention is illustrated in connection with an evaporator core of rectangular cross-sectional shape and having a plurality of refrigerant conduit sections which carry the refrigerant in parallel paths. Each conduit section comprises a plurality of lengths of tubing which run back and fonth through the core. The axes of the lengths of tubing are arranged in a predetermined pattern such that the conduit sections may be nested in groups of two, with the inlets and outlets of each pair of conduit sections being adjacent each other. In particular, the tube axes are arranged in rows parallel to and at right angles to the core thickness, and when taken together the rows for each pair of nested conduit sections form a grid-like pattern with each intersecting point of the grid marking the position of one length of tube. Several pairs of sections may be combined to form the completed core, each pair being arranged in the manner aforesaid. When so constructed, the completed evaporator core will have all the outlet ends of the conduit sections along one edge so that a single header may be provided therefor. The inlet connections ifor the sections will likewise lbe disposed in a line. This invention is particularly directed to capillary entrances of a permanent or removable type which are provided at the inlet ends of the conduit sections.

Referring to the drawings, the evaporator core comprises a pair of supporting brackets |11 and 12 disposed at opposite ends thereof. Extending between these brackets are a plurality of tubes generally indicated at 13 which are connected to -forrn the refrigerant conduit sections. A plurality of cooling iins 14 are mounted on tubes 13 in a conventional manner and serve as secondary surface areas for the evaporator. -It will be understood that tubes 13 and cooling iins y14 could be constructed in various manners, and in particular may be made in ac- 3,38Z Patented Apr. 24, 1962 cordance with the principles taught in my Patent No. 2,134,665, dated October 25,11938.

The arrangement of conduit sections is best seen in FIGURE 3 which shows in detail the manner in which tubes 13 are connected to form one pair of nested conduit sections, and which further shows the positions of the inlet and outlet connections for the remaining pairs of conduit sections. It will be noted from this ligure that both the inlet and outlet connections are supported by bracket 12, bracket 11 carrying return connections between the various tube lengths. The inlet connections or manifolds are indicated at 15 and are shown in detail in FIGURE 4. Each inlet connection comprises a cupshaped member 15a having a central opening to which is connected a supply tube 16 with liquid refrigerant. Each inlet 15 supplies liquid refrigerant to a pair of conduit sections. These conduit sections are indicated generally at 17 and 1.8 respectively `for that inlet 15 which is found at the lower right hand corner of FIGURE 3.

In describing the arrangement of the conduit sections it is perhaps best to trace section 17 from inlet to outlet, and then trace section E1S to demonstrate the manner in which the sections are nested. The tirst length of tube in section 17 is indicated at 19 in FIGURE 3. It will be noted that this tube is in the extreme lower righ hand corner of the evaporator core, and the tube will carry liquid refrigerant from inlet 15 in a direction passing into the paper. This ow direction is indicated by the conventional arrow-tail symbol in FIGURE 3. When the refrigerant reaches the far end of tube y1.9 it will be reversed in flow by a return member 21 of cup-shaped configuration which, while reversing the flow of refrigerant, maintains it in a plane parallel to the core thickness. The fluid will then flow back through the core by means of tube 22 indicated in FIGURE 3, and when it reaches the other end will again be reversed in flow by a return connection 23 similar to connection 21. The fluid will then flow through tube 24 until it reaches the other end of the core where it will be reversed by a return connection 25. The fluid will neXt ow back through tube 26 toward the end of the core supported by bracket 12. It will be noted that when flowing through tubes 22 and 26 the luid will ilow in a direction out of the paper in FIGURE 3, and this ow is represented by the conventional arrowhead. The ilow direction into the paper through pipes 24 and 19 are represented by arrow-tails. It should be observed that the axes of pipes 19, 22, 24 and 26 are evenly spaced and are all in the same plane traversing the thickness of the evaporator core.

After leaving tube 26 the refrigerant is lead through a return connection 27 to a tube 23. Connection 2'7 differs from the previous return connections in that it is disposed in a plane at right angles to the core thickness, and tube 23 is at a level above that of the previous tubes. The refrigerant will flow through tube 28 and will then be reversed in flow by a return connection 29, after which it will return through a tube 31. Connection 29 is in the same plane las connection 27 and after leaving tube 31 the lluid will be conducted through a return connection 32, also in the same plane, and will next pass through a tube 33 one level above tube 31, tubes 26, 23, 31 and 33 being evenly spaced.

After leaving tube 33 the huid will pass through a return connection 34 which is again in a plane parallel to the core thickness and will then ow through a tube 35. A return connection 36 will cause the fluid to ow next through a tube 37 lin the sarne plane as tubes 33 and 35. A return connection 3S at the end of tube 37 and at right angles to the core thickness will conduct the fluid to a tube 39. It should be noted at this point that tubes 37 and 39 are in the same plane as tube 22. The uid will next liow through a return connection 41 to a tube 42, the latter being at the same level as tube 39 l and immediately above tube 35.

Upon leaving the tube 42 the fluid will pass through a return conduit 43 after which it will How through a tube 44, finally returning to that end of the core supported by bracket 12. Tube 44 is in the same plane as tubes 39 and 42 parallel to the core thickness and is in a common plane with tubes 26, 28, 31 and 33 at right angles to the core thickness. Upon leaving tube 44 the evaporated fluid will enter an outlet connection 45 which is 'visible in FIGURES l and 3. This outlet connection also serves to receive the evaporated fluid leaving conduit section 18, and a manifold or header 46 is provided for receiving evaporated fluid from the plurality of outlets 45 which are on the evaporator core.

In reviewing the arrangement just described for conduit section 17, it will be apparent that the section is made up of twelve tube lengths divided into ve groups or legs, the legs being alternately parallel to and at right angles to the core thickness. The first leg (tubes 19, 22, 24 and 26) traverses the entire thickness of the evaporator core. The next leg (tubes 26, 28, 31 and 33) extends in the direction of the length of the core While the third leg (tubes 33, 35 and 37) is again in the direction of the core thickness. The fourth leg (tubes 37 and 39) is in the direction of the core length and the fifth leg (tubes 39, 42 and 44) is in the direction of the core thickness. It should also be observed that since the legs in the direction of core thickness are in overlapping relation, the maximum thickness of the entire conduit section is only four spaced tube lengths.

The arrangement of conduit section 18 is such that it interts with section 17 so as to maintain a maximum thickness for the core of only four spaced tube lengths. The first ltube through which the fluid flows in section 18 from inlet 15 is indicated at 47 in FIGURE 3, the fluid owing into the paper as shown in this figure. By means of appropriate return connections, the iluid next flows through tubes 48 and 49 which are aligned with tube 47 in the direction of core thickness, tube 28 of conduit section 17 also being aligned with these tubes. It Will be noted that these tubes are also aligned with tubes in conduit section 17 in planes at right angles to thecore thickness. In particular, tube 47 is aligned with tube 19 while tubes 48 and 49 are aligned with tubes 22 and 24, respectively. The fluid next flows through a tube 51 which together with tube 49 forms a leg in the direction of the core length. The fiuid will then flow through tubes 52 and 53 forming a leg in the direction of the thickness of the core. A leg in the `direction of the core length is then provided, this leg being formed by tubes 54, 55 and 56 together with tube 53. A leg in the direction of the core thickness is next provided, constituted by tubes 56, 57, 58 and 59. The fluid leaving tube 59 will enter the same outlet connection 45 which receives the fluid from tube 44.

An examination of the arrangement of conduit sections 17 and 18 in FIGURE 3 will reveal the compact nested character of fthe sections. It will be ynoted that the legs of section 18 formed by tubes 47, 48, 49, 51 and 52 are nested within the legs of conduit section 17 formed by tubes 19, 22, 24, 26, 28, 31, 33, 35 and 37. Similarly, the upper leg sections of conduit section 17 are nested within the surrounding legs of conduit 18. The axes of the tubes `are located on the intersections of evenly spaced planes which criss-cross each other in directions parallel to the thickness and length of the evaporator core, thus affording maximum exposure of all tubes for evaporating purposes. Tubes are loca-ted at every one of these intersections so that no portion of the space occupied by the evaporator core remains unutilized. Each of the conduit sections 17 and 18 affords a maximum amount of travel for the refrigerating fluid, thus facilitating evaporation. Both sections 17 and 18 are of equal length so that there will be no disparity in degree of evaporation between portions of the fluid passing through the sections. Since sections 17 and 18 -run alongside each other from their inlet to their outlet ends, the temperature gradient between `the sections will be kept at a minimum thus increasing Ithe efficiency of the device.

The remainder of the evaporator core is made up of duplicates of conduit sections 17 and 18. The evaporator core of the illustrated embodiment is composed of a total of three such groups of conduit sections, these being numbered 61, 62 and 63. Since groups 62 and 63 are identical with group 61 described above it is not necessary to review them in detail. However, it will be noted that there is no gap left between the ends of adjacent groups so that all lines of intersection of the evenly spaced planes mentioned above `are occupied by refrigerant carrying tubes. Since all the outlet connections are aligned as seen in FIGURE 3, header 46 may be used to collect the evaporated refrigerant yfrom all conduit sections of the core, from which it may be delivered to an accumulator 64 or to some other portion of the refrigerating system.

In operation, liquid refrigerant will be led to all the inlet connections 15 from the refrigerating system, four such connections being shown in the illustrated embodiment. The liquid refrigerant will pass into the conduit sections 17 and 18 which constitute each of groups 61, 62 and 63. When passing through these parallel paths the evaporating liquid will traverse equal distances in both conduit sections, and the evaporated fluid will exit through outlet connections 45 to header 46. It will be understood of course that any number or all of groups 61, 62 and 63 may be utilized depending upon requirements.

Coming now to the features claimed herein, FIGURES 4 and 5 illustrate two embodiments of capillary entrances or calibrated nozzles which are provided at the inlet ends of the conduit sections. Capillaries such as those shown serve to increase the agitation and dispersion of the iluid supplied to the conduit sections. In the case of the illustrated evaporator, this fluid is liquid refrigerant, and the capillaries increase the evaporation of the refrigerant and, in addition, meter the flow of refrigerant tov the conduit sections.

In FIGURE 4, the cup-shaped member 15a has its open end or rim 63a partially closed by a plate 65 having a pair of capillary tubes 66 and 67 punched or otherwise formed therein. The plate 65 is secured by brazing 67a, or the like, at its edge to the rim of the member 15a. Tubes 68 and 69 are shown as formed integrally with a bottom closure plate 65a `and disposed in positions enclosing capillary tubes 66 and 67, respectively. The closure plate 65a has an annular ange 65h which surrounds the rim 63a and is secured by brazing 65C, or the like, to the cup-shaped member 15a at a position such that the capillary tube plate 65 is disposed between the closure plate 65a and the rim of the cup member 15a to positively maintain the capillaries 66 and 67 in positions projecting into the tubes 68 and 69 which t within and have a substantially smaller diameter than the inlet tubes 19 and 47 with which they are associated the parts being brazed or otherwise secured together. With this construction it will be seen that liquid refrigerant entering inlet 16 to connection 15 will pass through tubes 66 and 67 into the inlet ends of the inlet tubes 19 and 47, respectively.

FIGURE 5 shows a modied construction in which the capillary tubes 71 and 72 are threadably mounted in a plate 73 secured at its edge by brazing 73a or the like to the rim 81 of a cup-shaped member 74 which corresponds to the member 15a and is disposed on the outer side of plate 73.

A closure plate 79 is located on the opposite side of the plate 73 and has an annular ange 82 which surrounds the rim 81 and is secured by brazing 83, or the like, to the cup-shaped member 74. The closure plate 79 is secured by brazing 84 to the plate 73 `and is formed integrally with tubes 75 and 76 Which are coaxial with and surround the capillaries 71 and 72, respectively. A pair of removable plugs 77 and 78 are threadably mounted in the cup-shaped inlet member 74 opposite the capillaries 71 yand 72. In this manner the capillary tubes may be removed and replaced for maintenance purposes.

Although the invention has been described with respect to a preferred embodiment thereof, it is to be understood that it is not to be so limited, since changes can be made therein which are Within the scope of the invention as delined by the appended claims.

What is claimed is:

1. In an evaporator which includes a pair of conduit sections having their inlet ends positioned adjacent each other, an inlet manifold connected to said inlet ends for supplyingrefrigerant under pressure to said conduit sections, said manifold having a refrigerant inlet opening, and capillary tubes punched out of said inlet manifold and projected into said inlet end so that `all of the liquid refrigerant supplied to said conduit sections ilows through said capillary tubes, said capillary tubes being of a cross sectional area which is less than the cross sectional area of said manifold inlet opening.

2. An evaporator which includes a pair of conduit sections having their inlet ends positioned adjacent each other, a manifold member connected to said inlet ends, said manifold member having an inlet opening adapted to receive refrigerant under pressure and capillary tubes removably mounted on said manifold member and projected into the inlet ends of said conduit sections, each of said capillary tubes having an orice of lesser cross sectional area than said manifold inlet opening through which all of the uid owing into the associated conduit section must How, whereby the flow of fluid into said conduit sections is restricted and the fluid is agitated and dispersed upon its entry into said conduit sections.

3. An evaporator which includes a pair of conduit sections having their inlet ends positioned adjacent each other, a manifold member connected to said inlet ends and having a refrigerant inlet opening and capillary tubes threadably mounted on said manifold member and projected a short distance into the inlet ends of said conduit sections, said capillary tubes having orifices of a lesser cross sectional area than said inlet openings for restricting the flow of refrigerantinto said conduit sections and dispersing and agitating said refrigerant as it is emitted into said conduit sections.

4. An evaporator which includes a pair of conduit sections having their inlet ends positioned adjacent each other, a manifold member connected to said inlet ends,

`an inlet member for refrigerant connected to said manifold member, capillary tubes of a lesser cross sectional area than said inlet member removably mounted on said manifold member and projected into the inlet ends of said conduit sections for increasing the agitation and dispersion of refrigerant supplied to said conduit sections from said manifold member, and removable plugs mounted on said manifold member at positions in substantial axial alignment with said capillary tubes.

References Cited in the tile of this patent UNITED STATES PATENTS 2,138,187 McElgin Nov. 29, 1938 2,327,663 Otis Aug. 24, 1943 2,688,237 Beane Sept. 7, 1954 2,707,868 Goodman May 10, 1955 2,896,429 Karrriazin July 28, 19,59 

